If it really is black then now worries ! get the feul reduced a little and smoke will dissappear, carb setting is very sensitive thing I dont get my carb open very often, only got it cleaned5/6 times in my total experience with this bike, even this count is high according to me ....
Pakistan men carburetor ki setting ky magicians rahty hain go to some Good reputed mechnic who is in touch with racers wheelers they have very good in hand experince.
Do get the compression checked as well, may be your bike rings are getting lose (if rings are depricating mostly smoke color is not black so dont worry but still get it checked)...